Experimental investigation of Al2O3 nanosuspension in vapor compression refrigeration system using tetrafluoroethane and iso-butane refrigerants

Abstract

The indirect emissions due to energy consumption by refrigeration system has contributed potentially to global warming. The infusion of nanoparticle-based suspension (nanofluid) have shown significant improvement in heat transfer for refrigeration application with the noteworthy reduction in energy consumption. Experimental work was carried out with an aim to reduce indirect emissions from the refrigeration system. Thus, the present work consist of the performance investigation of aluminum oxide (Al2O3) nanoparticle suspension in a vapor compression refrigeration system with varying refrigerant mass charges. The refrigerants used for the experiment are tetrafluoroethane (R134a) which is high in GWP (Global Warming Potential) and isobutane (R600a) which has low GWP. Mineral oil (MO) and POE (Polyolester Oil) were used as the base fluid for the synthesis of Al2O3 based nanofluid with mass fractions of 0.02%, 0.04%,0.07%, and 0.1%.Varying mass charges of 150 gm, 180 gm, and 200 gm of R134a and R600a refrigerant were employed in the experiment to work with each mass fraction of nanofluid. The refrigeration system is designed to work within the cycle range of −6 °C to 30 °C for R134a and R600a refrigerant. Experimental results showed improvement in COP by 41.8%, reduction in power consumption 31.85%, increment in compressor discharge pressure by 12.56%, reduction in evaporator pressure by 3.94%, and reduction in pull-down time by 23.5% by using 200 gm of R600a-MO with 0.1 wt% of Al2O3 based-suspension. Also, there is a significant reduction in exergy destruction observed in a different component of the refrigeration system by using the nanosuspension compared to the pure refrigerant.